LED device for wide beam generation

Abstract

An apparatus and method is characterized by providing an optical transfer function between a predetermined illuminated surface pattern, such as a street light pattern, and a predetermined energy distribution pattern of a light source, such as that from an LED. A lens is formed having a shape defined by the optical transfer function. The optical transfer function is derived by generating an energy distribution pattern using the predetermined energy distribution pattern of the light source. Then the projection of the energy distribution pattern onto the illuminated surface is generated. The projection is then compared to the predetermined illuminated surface pattern to determine if it acceptably matches. The process continues reiteratively until an acceptable match is achieved. Alternatively, the lens shape is numerically or analytically determined by a functional relationship between the shape and the predetermined illuminated surface pattern and predetermined energy distribution pattern of a light source as inputs.

We claim: 
     
       1. A luminaire comprising:
 a plurality of light modules; and 
 a fixture operable to position the plurality of light modules above an area to be illuminated, 
 wherein each light module comprises:
 a substrate; and 
 a quantity of light sources mounted to the substrate, each light source comprising:
 at least one light emitting diode; and 
 a lens positioned to accept light from the at least one light emitting diode, 
 wherein the lens exhibits symmetry with respect to a first reference plane that extends through the lens and the substrate, 
 wherein a second reference plane extends through the substrate and the lens and is substantially perpendicular to the first reference plane, 
 wherein the lens comprises a feature that is disposed on a first side of the second reference plane, and 
 wherein the feature is operative to receive light propagating on the first side of the second reference plane and to redirect said received light through the second reference plane for propagation on a second side of the second reference plane so that the each light source in the quantity outputs a respective pattern of light that is biased to the second side of the second reference plane relative to the first side of the second reference plane and that has a respective intensity, 
 
 
 wherein each light module is operative to produce a pattern of light substantially matching said respective pattern of light with an intensity that is substantially equal to said respective intensity multiplied by the quantity. 
 
     
     
       2. The luminaire of  claim 1 , wherein the feature comprises a prism. 
     
     
       3. The luminaire of  claim 1 , wherein the feature comprises a refractive surface. 
     
     
       4. The luminaire of  claim 1 , wherein the lens comprises a depression disposed at an intersection between the first reference plane and a surface of the lens, the depression biased to a side of the second reference plane. 
     
     
       5. The luminaire of  claim 1 , wherein the area comprises a street that extends in a direction,
 wherein the fixture is configured to position the plurality of light modules such that the first reference plane is substantially perpendicular to the direction and the second reference plane is substantially parallel to the direction, and 
 wherein the respective pattern of light is biased street side relative to curbside. 
 
     
     
       6. The luminaire of  claim 1 , wherein the lens comprises two lobes, and
 wherein the first reference plane extends between the two lobes. 
 
     
     
       7. The luminaire of  claim 1 , wherein each light module comprises a heat sink that conducts and dissipates heat. 
     
     
       8. A street luminaire comprising:
 a plurality of light modules; and 
 a fixture that is configured to position the plurality of light modules for illuminating a street that extends in a direction, 
 wherein each light module comprises:
 a substrate; and 
 a number of light sources disposed adjacent the substrate, each light source comprising:
 a respective lens; and 
 at least one respective light emitting diode coupled to the respective lens, wherein the respective lens is intersected by a plane that extends in the direction, the plane having a street side and a curbside, and 
 wherein a portion of the respective lens is disposed on a curbside of the plane and is operative to receive light from the at least one respective light emitting diode that is headed curbside and to reflect said received light to pass through the plane, so that the respective lens produces an illumination pattern of an intensity, the illumination pattern biased street side relative to curbside, and 
 
 
 wherein each light module produces a scaled version of the illumination pattern, the scaled version having a second intensity that is approximately equal to the intensity multiplied by the number. 
 
     
     
       9. The street luminaire of  claim 8 , wherein the respective lens has a plane of symmetry that is substantially perpendicular to the plane,
 wherein the respective lens comprises two lobes, and 
 wherein the plane of symmetry extends between the two lobes. 
 
     
     
       10. The street luminaire of  claim 8 , wherein the portion of the respective lens comprises a totally internally reflective surface oriented for reflecting said received light. 
     
     
       11. The street luminaire of  claim 8 , wherein the plurality of light sources disposed adjacent the substrate form a two-dimensional array, and
 wherein the planes are substantially parallel to one another. 
 
     
     
       12. The street luminaire of  claim 8 , wherein the fixture is further operable to position the plurality of light modules substantially parallel to a surface of the street. 
     
     
       13. The street luminaire of  claim 8 , wherein when cast on a street surface, the illumination pattern is substantially symmetrical with respect to a line on the street surface that runs perpendicular to the plane. 
     
     
       14. The street luminaire of  claim 8 , wherein the illumination pattern forms a two-dimensional distribution of energy on a surface, and wherein the two-dimensional distribution of energy is divisible into two intensity patterns exhibiting substantial mirror image symmetry with respect to one another. 
     
     
       15. A street luminaire comprising:
 a first number of light modules, each operable to produce an illumination pattern with a first intensity; and 
 a fixture that is operable to mount and power the first number of light modules to produce the illumination pattern with a second intensity for illuminating a street, the second intensity substantially equaling the first intensity multiplied by the first number, 
 wherein each light module comprises a second number of light sources, each light source comprising:
 at least one respective LED; and 
 a respective optic comprising a first side that the fixture orients curbside and a second side that the fixture orients street side, 
 wherein the first side of the respective optic and the second side of the respective optic are optically different from one another, 
 wherein the respective optic is mounted with the at least one respective LED such that the first side of the respective optic receives light from the at least one respective LED and the second side of the respective optic receives light from the at least one respective LED, 
 wherein the first side of the respective optic is operable to send street side a substantial amount of the light that the first side of the respective optic receives, resulting in biasing the illumination pattern street side relative to curbside, and 
 wherein the respective optic is operable to produce the illumination pattern of a third intensity, and the first intensity substantially equals the third intensity multiplied by the second number. 
 
 
     
     
       16. The street luminaire of  claim 15 , wherein the respective optic exhibits optical symmetry with respect to a centerline that is substantially perpendicular to the street. 
     
     
       17. The street luminaire of  claim 15 , wherein the respective optic comprises an outer surface comprising a plurality of lobes. 
     
     
       18. The street luminaire of  claim 15 , wherein the respective optic comprises a complex prism disposed on the first side of the respective optic. 
     
     
       19. The street luminaire of  claim 15 , wherein the illumination pattern provides a two-dimensional distribution of energy on a street surface, the two-dimensional distribution of energy divisible into two intensity patterns exhibiting mirror image symmetry with respect to one another. 
     
     
       20. The street luminaire of  claim 15 , wherein the second side of the respective optic and the first side of the respective optic differ from one another due at least to one different internally reflective feature and one different refractive feature.